Retro game engine for creating games like it's 1997
A modern, cross-platform Quake game engine based on FitzQuake.
Open source FPS/RTS Game
Game engine for playing tomb raider 1 - 5 levels.
Quake C mods and support - SSQC / CSQC
A Quake III Arena Mod.
Free and open source FPS based on Quake III Arena